HIRANUMA APPLICATION DATA

Watercontents

Karl Fischer Titrator

Data No.

KF1

Mar. 82018

Hydrocarbon, Halogenated hydrocarbon

1. Abstract
Water content of hydrocarbon and halogenated hydrocarbon could be determined by Karl Fischer
coulometric titrator. In coulometric titration, iodine of Karl Fischer reagent is generated by electrolysis andgenerated iodine quantitatively reacts with water. Reaction formula is described below.
H2O ＋ I2 ＋ SO2 ＋ 3RN ＋ CH3OH → 2RN・HI ＋ RN・HSO4CH32RN・HI → I2 ＋ 2RN ＋ 2H＋ ＋ 2e－Hydrocarbon and halogenated hydrocarbon do not interfere the Karl Fischer reaction and direct injection
method could apply. Anode solution is selected in accordance with sample solubility. General use of anodesolution contain methanol as solvent. When the sample like a long chain hydrocarbon have poor solubility inmethanol, anode solution containing chloroform or hexanol or toluene is used. When fritless cell is used,cathode solution is not necessary.

2. Apparatus and Reagents(1) Apparatus
Titrator：

Hiranuma Karl Fischer Coulometric titrator

Electrolytic cell：Standard Cell

AQ-series

Fritless Cell
(2) Reagents
Anode solution：

Hydranal coulomat AG (Honeywell)

Cathode solution：

Hydranal coulomat CG (Honeywell)

3. Procedure(1) Fill 100 mL of anode solution and one ampoule of cathode solution into the electrolytic cell as shownin Fig.3.1.
(2) Start blanking to attain stable background.
(3) Wash the syringe with sample.
(4) Draw the sample into syringe and then weigh the syringe.
(5) Inject sample from rubber septum of electrolytic cell as shown in Fig.3.2.
(6) Start titration. Measurement parameter is shown in Table 4.1.
(7) Weigh the syringe again and then set the difference of weight to sample size.

Cathode solution

Anode solution

Fig.3.1. Preparation of the reagents.
Note(1) Do not touch the tip of needle toanode solution.
(2) When injecting, set the tip ofneedle as below figure.

(3) Before pulling out the needle,
draw alittle

airdripping of sample.

Fig.3.2. Injection of sample.

4. Parameters and results
Table 4.1. Parameter.
Condition File
Cal ModeInterval Time
CurrentS.Timer
Blank Value
Unit Mode
Auto Interval
Minimum Count
Back Ground
Sample Size Input
Cell Type

0:Sample weight (net)
X=(H2O-BLANK)/SIZE20
SLOW00
AUTO
05ON
Every Time
Standard / Fritless

secminuggug

topreventTable 4.2. Results of water content measurement in hydrocarbons.
SampleApparatus

Cell

Reagent

SampleSize (g)Water(μg)

Water Content(ppm)

Heptane

AQ

StandardAG

1.0418

35.6

34.2

CG

1.061734.4

32.4

1.093634.8

31.8

1.142536.8

32.2

1.068833.1

31.0

1.0431

32.6

31.3

AG

2.9461

88.1

29.9

CG

2.979893.0

31.2

2.907189.9

30.9

2.772984.6

30.5

2.925385.8

29.3Fritless

Chloroform

AQ

Standard

Fritless

Cyclohexane

AQ

Standard

Fritless

Isooctane

AQ

Standard

Fritless

AGAG

2.9486

90.7

30.8

AG

1.5958

61.9

38.8

CG

1.579159.0

37.4

1.579559.9

37.9

1.603960.2

37.5

1.538457.7

37.5

1.6157

60.1

37.2

AG

1.32027

63.7

48.2

CG

1.47262

71.8

48.8

1.43564

69.9

48.7

1.43916

68.0

47.2

1.42384

66.2

46.5

1.44880

69.9

48.2

AGAG

Statistics Results

Avg. 32.8 ppm
SD 1.2 ppm
RSD 3.8 %Avg. 31.5 ppm
SD 0.6 ppm
RSD 2.0 %Avg. 30.7 ppm
SD 0.7 ppm
RSD 2.2 %Avg. 30.2 ppm
SD 0.8 ppm
RSD 2.6 %Avg. 38.0 ppm
SD 0.7 ppm
RSD 1.9 %Avg. 37.4 ppm
SD 0.2 ppm
RSD 0.5 %Avg. 48.6 ppm
SD 0.3 ppm
RSD 0.7 %Avg. 47.3 ppm
SD 0.9 ppm
RSD 1.8 %5. Note(1) Use dried syringe and syringe vial at sampling for prevention of contamination by atmospheric water.

(2) To measure 100 µg or less water detection, make sure stability of blanking. Low and stablebackground value is important factor for trace level of water measurement.
(3) Select anode solution according to the solubility of the sample. For example, Hydranal Coulomat
AG-H and Oil are suitable for long chain hydrocarbons and oils.
(4) The optimized electrolysis control for fritless cell of AQ series released after 2009 improves themeasurement accuracy of fritless cell. It can be used with the evaporator as well. Suitable reagent for
fritless cell is required. For example, Hydranal coulomat AG and AG-Oven are compatible with fritlesscell.
Keywords：Karl Fischer, Coulometric titration, Direct injection, Hydrocarbon, Fritless cell